QYT KT 8900 and Variants RF Finals (AFT05MS006NT1)

Datasheet for RF Finals for QYT KT8900 Juentai JT-6188 aka MP300, 8900mini
VHF / UHF Compact Mobile Frequency Range 136-174 / 400-480 MHz

Download here

10 replies on “QYT KT 8900 and Variants RF Finals (AFT05MS006NT1)”

Boa Noite! Algum colega teria disponivel o schematic do QYT KT7900D ou a Firmware para update desse equipamento? O meu radio ao energizar ligar dar o power ele ja entra em TX e apos o tempo de programa;’ao que deixei 15segundos ele automaticamente entra na tela normal mas porem fica inoperante nao transmite e nem recebe ou melhor sem TX e RX! Para eu conseguir ter RX vou na fun;ao MONI ai funciona!

Why are the replacement finals in your link only rated for 6w @ 7.5 volts?
if the radio is rated @ 25w @ 13.5 volts .. How then do they get 25w output ?

I do see finals rated @ 25w and 16w @ 13.5v. (NXP)
Thanks for all your great help and information.

Robert – N3BZ

It looks like that they overdrive the RF finals, it can support a 3dB overdrive @ 10.08vdd with no device degradation as referenced on the datasheet, however due to heat sink construction and placement on the PCB it cannot absorb the extra heat being generated by the device which causes premature burned RF finals on most QYT KT8900. If you have one you can check out the RF finals on your radio and you will see that it has the same RF finals with 6W output rating installed on it.

Thanks you for your reply !

Yes, I am seeing same .. and repairing units w/ correctly rated devices.
The 6/7/16w watt versions from ST/NXP in powerso-10 packages are inexpensive
per say (~$6 us) … where the 25w device is much more expensive (~$29 us).

Does anyone know of a manufacturer which can provide 12v@25w which can
is less then the above price?

Thanks –
Robert – N3BZ

I’m not sure of any other manufacturer that can provide that, since I also imported that device from China through ali express, when mine blows up. It’s not available here locally although NXP have a factory in Calamba, Philippines they are probably selling it to those companies that manufactures low cost radios in China exclusively.

Kt 8900 saya ga bisa transmit,walaupun finalnya sudah di ganti baru mohon penjelasan yang lainnya.terima kasih

Check the diagram if there are other issues with the radio, if radio finals is the problem your radio can at least transmit on very short distance if there are other issues for sure the RF signal is not going through the RF finals so there must be other fault in the radio’s circuit.

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